Tuesday, March 22, 2011

Tis' the Season for Cool Season vs. Warm Season Plants

Marigolds and Pansies, Together, in Winter

It's a nice, sunny Saturday in February or March. You decide to do a little shopping, perhaps picking something up for the garden. Off you go to the big box store, the local nursery or (gulp!) the local drugstore or supermarket (which, you may have noticed lately, has that alluring display of colorful annuals and vegetables outside the front door).

You got everything together so you can get out of the driveway...keys, credit, cash, a coffee. Um, wait a minute, before you leave the house...
Do you have any frickin' idea what you are going to buy? No?
You, then, will be crowned "Garden Customer of the Day" wherever you shop. That's because you'll be impulse buying, spending more money on plants that may or may not be right for you and your yard.
But this rant isn't about your shopaholic ways. Another day for that (hint: survey the yard for your needs; make a list or garden plan; stick to it).
No, this rant is about something every gardener should carry in their car and grab it when they walk into a nursery section: a good plant reference book.

Western Garden Book: More 
than 8,000 Plants - The Right Plants for Your Climate - Tips from 
Western Garden Experts (Sunset Western Garden Book)

Here in California, it's hard to beat the Sunset Western Garden Book for that purpose.

Updating your old Sunset Western Garden Book? Fine. Put the old one in the car trunk.

The Southern Living Garden
 Book: Completely Revised, All-New EditionElsewhere in the country, good references include the Southern Living Garden Book.

Also, look for the Northeastern Garden Book (a great reference for gardeners at higher elevations in California) or the National Garden Book (if you can still find it!).

Northeastern Garden Book
Sunset National Garden 
Why approach a place of business that's selling plants with such a reference book? Those plants may be there either a) too late in the season; b) too early in the season; or, c) mixed together so that you can't tell whether they are cool season or warm season annuals.

Late Winter-Early Spring Culprit #1:
The Mixed Bag O' Plants Display

Summer vs. Winter: Marigolds next to Violas
An eye-catching rack of annuals and vegetables outside the front door of supermarkets and drugstores.
Here in California, buying cool season annuals - flowers that will disappear with the heat of mid to late spring - is not a bad idea in February or March...if you are planning an outdoor event in April through mid-May. Those cool season annuals will be outstanding at that time. 

Summer annuals, on the other hand, will be just starting their growth spurt. But if you are looking for color that will last all summer - and you live in a hot summer area - choose warm season annuals for color from April through October.

Recipe for Plant Death: Cucumbers in February
Culprit #2: 
"Too Soon!" Vegetables.

February and March is still too iffy to be planting many warm season annuals (flowers and vegetables) outdoors in Northern California. Soil temperatures - and warmer weather - will arrive in mid-April. Cucumbers, beans, eggplant, melons, peppers, pumpkin and other squash need soil temperatures of at least 60 degrees. In February and March, soil temps are still in the 40's and 50's in most areas of Northern California. Here's a link to a previous post containing the soil temperature requirements for various vegetable seeds.

Culprit #3: 
Alluring beauties that have just arrived from the Tropics. 
This bougainvillea was shaking its hips outside a local grocery store. In early March. Literally, shaking. It was a 40 degree day with 40 mph winds. Subjecting a greenhouse-grown plant to harsh, outdoor conditions suddenly can induce dormancy and stress, attracting a wide variety of insects and disease. Bougainvilleas can live year after year in the mild climates of the Bay Area or coastal Southern California. Here in Sacramento, where winter temperatures regularly drop to freezing many mornings, that bougainvillea is best treated as a summer annual. Which is a polite way of saying: it will die back in the winter. It might revive the following spring, or it might not. Depends on its location in the yard, preferring an area with reflected heat, such as against a south or west-facing wall. Again, wait until April before subjecting these tender plants to our outdoor world.

A good reference book while plant shopping can help you answer such questions as:
• Is the plant I am looking at REALLY that plant? (compare it to the plant description in the book).
• When is the best growing season for this plant?
• Do I really want this particular variety of plant? (For example, a Beefmaster tomato can offer up large slicing tomatoes all summer; a Roma tomato, though, tends to set smaller fruit all at once which makes it ideal for canning purposes)
• Do I have the right spot in my yard for this plant: Does it require sun or shade? Quick draining soil? Lots of water or little water? Acid soil? Are any of its parts poisonous?

I realize that "sticking to a garden plan" is, well...challenging, especially when you meet up with a comely beauty at a nursery or grocery store. Still, arming yourself with a good reference book while shopping might give you more incentive to drive home, alone. 


  1. I like your suggestion to bring the reference manual to the garden center but I'll admit that I'm a little too self-conscious to haul around a big book like that. Besides, I usually have one hand tied up with a coffee and the other hand has to be be free to pick up the plants. With that said, I have been experimenting with different applications for my iPhone that will give me access to all the plant information I might need. So far nothing has been as complete or easy to access as the Sunset book though. So for now, I'm trying to do my homework ahead of time.

  2. The closest app I have found that approaches being a thorough digital garden encyclopedia is "Landscaper's Companion" for the IPad. But it still falls short of the Sunset Western Garden Book. Sunset, are you listening?

  3. It's good of you to take the time to help newbies make the distinction between cool-season and warm-season plants. I used to be pretty stern with myself about not using cool-season plants when I knew the warm-season stuff was coming in soon, but I've come to really appreciate mixed planters with both cool- and warm-season annuals. The cool-season annuals (i.e. pansies) provide color now and the warm-season plants provide color later. The in-between stage where they're both blooming is lovely. It's a recipe that works well and you can always yank the cool-season stuff when it starts to peter out. I guess I'm becoming more relaxed about the whole subject. It's more fun that way. ;-)

    A Western Garden Book App would be SWEET!!!!!